Acropora palmata is listed as threatened under the U.S. Endangered Species Act. Image: William Precht/Dial Cordy and Associates, Inc.

A study has found the oldest genotypes of Acropora palmata (elkhorn corals) are over 5,000 years old. Put another way: reefkeepers can still be trading the same frag genes of today's "designer corals" many millennia from now.

No; not that kind of sponge filter. I want to talk about living sponges. These sedentary animals may look passive, but they are anything but. Their active water pumping mechanism is really impressive.

Most of us know that sponges are filter feeders, but some of us (and a large portion of the general public) think of sponges as passive organisms that essentially soak up food like, well, a sponge. Nothing could be further from the truth!

Sponges actively pump water through their osculums (AKA "little mouths") by using an army of tiny flagella (threadlike appendages) flapping like microscopic madmen to push water through the sponges' chambers.

The drawing to the right by the Marine Education Society of Australasia shows how this mechanism works. And the video below shows how efficiently sponges can process large volumes of water through their systems.

Lubricogobius tunicatus is a new Indo-Pacific dwarf goby (mature size of about 0.4"/1cm) that lives inside the oral or incurrent siphons of tunicates – just another fascinating symbiosis found on reefs.

About three quarters of coral species broadcast spawn (eggs and sperm) into the water for external fertilization. Fewer corals fertilize internally, brooding "baby corals" (scientists call these planulae) before "giving birth." Mediterranean sun corals are one such coral, and their way of giving birth is even more rare and weird.

Some of us think that reef fish can't see the color red because red light is quickly filtered out by seawater. But then why are so many reef fish fluorescence red? Studies are showing that reef fish not only see red, but the color serves very different purposes for different fish.

Dr. Tim Wijgerde has been perfecting his time-lapse photography. His latest 4K video reveals the slow motion of lovely Acropora polyps. Old timers will remember the days when Acropora were considered impossible to keep in captivity. Oh, how times have changed.

Amblygobius calvatus and Amblygobius cheraphilus are the two newest species of burrowing gobies from the tropical western Pacific Ocean. They exist in shallow water but are skittish and have evaded discovery until now.

This betta sold for an incredible $1500USD. Photo via Kachen Worachai's Facebook page.

The winning bid on a Facebook auction for a betta fish pigmented like Thailand's national flag ended at a whooping 53,500 baht (~$1,500 USD)! As far as we are aware, this makes it the most expensive betta fish in the world.

You likely know about the wiggly lures some frogfish use to entice prey to come within striking distance so the frogfish can easily ambush them. It turns out the lures of Antennarius striatus glow under actinic lighting, further enhancing their deadly seduction.

W00T! Researchers report a large-scale synchronous spawning of ~2800 colonies of outplanted Acropora tenuis in Okinawa, Japan. This is a different method of reef restoration than what many of us are familiar with - one which promotes genetic diversity through natural reproduction.